Rosalyn Suffers from Obsessive-Compulsive Disorder

Rosalyn suffers from obsessive-compulsive disorder.What would the neuroscience model say is the cause of Rosalyn's disorder?

A) She has unconscious conflicts that centre around her fixation at the anal stage.
B) She has a distorted view of herself that has prevented her from achieving personal growth.
C) She has a chemical imbalance in her brain.
D) She has learned this behaviour as a coping mechanism in response to her unwanted thoughts.